Expanding catheters are commonly used in surgical procedures to remove emboli or blood clots from an occluded branch or vessel. An embolus is most frequently a blood clot, but it can also be plaque broken off from an atherosclerotic blood vessel or a number of other substances including fat, air, and even cancerous cells. Typically, the catheter is inserted percutaneously to the vicinity of the clot and expanded, capturing a portion of the clot, which is then withdrawn from the vessel upon removal of the catheter. One mechanism for expansion of a catheter is inflation.
Catheters with inflatable balloon means have been provided for blood clot removal. U.S. Pat. No. 4,762,130 to Fogarty discloses such a catheter. The Fogarty device uses a single, spiral-configured balloon U.S. Pat. No. 6,254,571 to Hart discloses a second type of catheter for removing occlusive materials from body passages, in which a plurality of mechanically activated expandable segments are disposed on the distal end of a catheter.
Embolectomy catheters have also been provided with balloons having small flexible protrusions adapted to bite into the clot upon inflation of the balloons, enabling a portion of the clot to be pulled free by withdrawal of the catheter. Such a catheter is shown in U.S. Pat. No. 3,635,223 to Klieman. Various other means for removing emboli exist, including coil-shaped and basket-shaped devices, which typically are constructed of wire or the like. None of these are consistently effective for clot removal, largely because new clots tend to be less organized and therefore more delicate.
Existing expandable catheters may suffer from several other problems. For example, if such a catheter comprises a single balloon and it is inflated near a well-organized clot, expansion of the balloon may result in the application of excessive force to the delicate vessel wall. Second, if a single expanded balloon catches the clot and the clot is large, the process of removing the clot may also create excessive forces on the vessel. Such procedures may damage the wall of the vessel. Expanding catheters that do not engage most of the clot mass may not trap and retain a large portion of the clot, especially upon withdrawal of the catheter from the vessel. Furthermore, present catheters do not present a low enough profile for easy insertion into extremely small diameter vessels such as those found in the brain.
Accordingly, there remains a need in the art for an angioplasty or embolectomy catheter that can capture, retain, and remove all or a significant portion of the blood clot without producing excessive pressure on the vessel. In addition, there is a need in the art for devices that can be inserted into extremely small diameter vessels.